The Canadian AR-180B is NOT rifled to the end of the barrel. The fact that the flash hider/muzzle brake is integral to the barrel is what makes it long enough. Pinned, welded etc. does not count towards the overall barrel length. If the device is machined integral to the barrel (IE; one piece) it does count. There are a number of custom built barrels on ACR's and FS 2000's in Canada that have a flash hider machined integral to the barrel to keep the barrel length as non restricted even though the rifling is not that long.